1. Field of the Invention
The present invention relates to instruments such as automatic blood analyzing instruments which rely upon the selective absorbance of light passing through a sample of thin cross-section. In such instruments the sample chamber is generally oriented perpendicular to the axis of the optical path. This places the sample chamber in an inaccessible location wherein, if any part thereof is visible, it is only one edge thereof. Therefore, various contaminants including small bubbles, clots and residue coatings, which may be present in the sample chamber and which drastically affect performance, cannot be identified. Sample chambers are also often difficult to disassemble for cleaning, and cleaning procedures often result in lengthy device shutdowns.
2. Description of the Prior Art
U.S. Pat. No. 4,134,678 teaches an instrument in which the sample cuvette is held perpendicular to the optical axis by a removable frame. In order to visually monitor a sample, the holding frame and cuvette must be removed from a temperature regulated zone, thereby necessitating a warm-up period after the cuvette is replaced in the instrument. When the cuvette holder is removed from the instrument it is mounted on a cuvette clip on the front plate of the instrument. A light source adjacent to the cuvette clip allows the operator to see whether there is a blood clot, impurity, bubble or other foreign substance in the cuvette.
U.S. Pat. No. 3,972,614 teaches a sample chamber which is situated within the housing of an ultrasonic hemolyzer. The sample chamber can be visually inspected only after, dismanteling the hemolyzing unit, whereby the instrument is subjected to a significant period of inoperability.